dissenting.
Reynolds v. Sims, 377 U. S. 533, laid down a “one man, one vote” mandate for the structuring of all state legislatures, but the Court there recognized, as it does again today, that “mathematical exactness ... is not required,” ante, at 443, and that variations are acceptable if they “are based on legitimate considerations incident to the effectuation of a rational state policy . . . .” 377 U. S., at 579, cited, ante, at 444. The Court refuses, however, to accept Florida’s present legislative apportionment plan, at least on the record before us, because neither the State nor the District Court justified the relatively minor variations in population among some of the districts.
This holding seems to me to stand on its head the usual rule governing this Court’s approach to the validity of legislative enactments; state as well as federal, which is, of course, that they come to us with a strong presumption of regularity and constitutionality. See, e. g., Butler v. Pennsylvania, 10 How. 402; Davis v. Department of Labor, 317 U. S. 249; Flemming v. Nestor, 363 U. S. 603. Accordingly, I do not believe the burden is on the State to justify every aspect of .a complex plan completely restructuring its legislature, on pain of its *448being declared constitutionally invalid by the judiciary. I can think of no other area of law in which there is an analogous presumption of invalidity attaching to a legislative enactment of a State in an area of its admitted competence and superior experience. The burden of showing unconstitutionality should be left here, as in other cases, on the attacking party.
I would affirm the judgment of the District Court on the grounds (1) that the plan enacted by the Florida Legislature is in substantial compliance with the rule of Reynolds v. Sims, supra, and (2) that the appellants have not shown any invidious purpose for, or effect flowing from, the mathematical variations among certain districts.